Protecting Drinking Water from Re-contamination

EPA scientists advance understanding of how biofilms in a drinking water system can harbor harmful bacteria following decontamination.

Under the Bioterrorism Act of 2002 EPA's responsibilities were expanded to address protecting water infrastructure associated with terrorist attacks. EPA fulfills this responsibility by conducting research on ways to prevent, mitigate, and recover from terrorist threats and attacks on water systems.

Most utility managers know how to treat and decontaminate their community's water system in the event of a bioterrorist attack. However, according to researcher Dr. Gene Rice, "…even after a drinking water supply has been treated, harmful bacteria can still exist in the pipes by living in biofilms." Biofilms are a collection of organisms adhering to a surface, and over time, they can build up inside of water pipes.

To address this issue, EPA researchers recreate biofilms under controlled conditions, allowing them to explore ways to remove biofilms from pipes.

Using an instrument called a Biofilm Annular Reactor, researchers can explore the effectiveness of methods (i.e. flushing or chlorination) to remove biofilms from pipe walls. These simulations are repeated under different conditions because not all biofilms are the same. Pipe materials (such as cement mortar and iron), water composition, and other variables can all affect how biofilms may react to decontamination and treatment efforts.

By testing biofilms and various treatment processes under many conditions, water utility managers, emergency responders, and remediation personnel can prepare for and recover from potential attacks in communities nationwide. This research helps to ensure that the treatment processes following a bioterrorist attack are thorough enough to ensure that drinking water is safe for consumption.